Hummingbird flight muscle is estimated to have among the highest mass-specific power output among vertebrates, based on aerodynamic models. However, little is known about the fundamental contractile properties of their remarkable flight muscles. We hypothesized that hummingbird pectoralis fibers generate relatively low force when activated in a tradeoff for high shortening speeds associated wit...

PURPOSE To describe the physical fitness of a top-level lower limb amputee (LLA) cyclist and paracycling time-trial (TT) race demands. METHODS The 40-y-old male unilateral transfemoral amputee TT World Champion was tested in a laboratory for peak oxygen uptake (VO2peak), ventilatory threshold (VT2), power output (PO), and hemoglobin mass (Hb-mass). Moreover, several measures (eg, PO, heart ra...

We investigated the effects of vagal reductions in O(2) delivery on oxygen consumption (VO(2)) in the anesthetized freshwater turtle Trachemys scripta. Specifically, these experiments tested the hypothesis that reductions in arterial oxygen partial pressure (PO(2)) and/or systemic oxygen transport (SOT) trigger a metabolic downregulation. During electric stimulation of the efferent branch of th...